/*
 * Copyright (C)  Tony Green, Litepal Framework Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.litepal.tablemanager;

import org.litepal.exceptions.InvalidAttributesException;
import org.litepal.parser.LitePalAttr;
import org.litepal.parser.LitePalParser;

import android.database.sqlite.SQLiteDatabase;

/**
 * The connector to connect database provided by LitePal. Users can use this
 * class to get the instance of SQLiteDatabase. But users still need to write
 * their own CRUD logic by the returned SQLiteDatabase. It will be improved in
 * the future.
 *
 * @author Tony Green
 * @since 1.0
 */
public class Connector {

    /**
     * LitePalAttr model.
     */
    private static LitePalAttr mLitePalAttr;

    /**
     * The quote of LitePalHelper.
     */
    private static LitePalOpenHelper mLitePalHelper;

    /**
     * Get a writable SQLiteDatabase.
     * <p/>
     * There're a lot of ways to operate database in android. But LitePal
     * doesn't support using ContentProvider currently. The best way to use
     * LitePal well is get the SQLiteDatabase instance and use the methods like
     * SQLiteDatabase#save, SQLiteDatabase#update, SQLiteDatabase#delete,
     * SQLiteDatabase#query in the SQLiteDatabase class to do the database
     * operation. It will be improved in the future.
     *
     * @return A writable SQLiteDatabase instance
     * @throws org.litepal.exceptions.InvalidAttributesException
     * @throws ParseConfigurationFileException
     */
    public synchronized static SQLiteDatabase getWritableDatabase() {
        LitePalOpenHelper litePalHelper = buildConnection();
        return litePalHelper.getWritableDatabase();
    }

    /**
     * Get a readable SQLiteDatabase.
     * <p/>
     * There're a lot of ways to operate database in android. But LitePal
     * doesn't support using ContentProvider currently. The best way to use
     * LitePal well is get the SQLiteDatabase instance and use the methods like
     * SQLiteDatabase#query in the SQLiteDatabase class to do the database
     * query. It will be improved in the future.
     *
     * @return A readable SQLiteDatabase instance.
     * @throws org.litepal.exceptions.InvalidAttributesException
     * @throws ParseConfigurationFileException
     */
    public synchronized static SQLiteDatabase getReadableDatabase() {
        LitePalOpenHelper litePalHelper = buildConnection();
        return litePalHelper.getReadableDatabase();
    }

    /**
     * Call getDatabase directly will invoke the getWritableDatabase method by
     * default.
     * <p/>
     * This is method is alias of getWritableDatabase.
     *
     * @return A writable SQLiteDatabase instance
     * @throws org.litepal.exceptions.InvalidAttributesException
     * @throws ParseConfigurationFileException
     */
    public static SQLiteDatabase getDatabase() {
        return getWritableDatabase();
    }

    /**
     * Build a connection to the database. This progress will analysis the
     * litepal.xml file, and will check if the fields in LitePalAttr are valid,
     * and it will open a SQLiteOpenHelper to decide to create tables or update
     * tables or doing nothing depends on the version attributes.
     * <p/>
     * After all the stuffs above are finished. This method will return a
     * LitePalHelper object.Notes this method could throw a lot of exceptions.
     *
     * @return LitePalHelper object.
     * @throws org.litepal.exceptions.InvalidAttributesException
     * @throws ParseConfigurationFileException
     */
    private static LitePalOpenHelper buildConnection() {
        if (mLitePalAttr == null) {
            LitePalParser.parseLitePalConfiguration();
            mLitePalAttr = LitePalAttr.getInstance();
        }
        if (mLitePalAttr.checkSelfValid()) {
            if (mLitePalHelper == null) {
                mLitePalHelper = new LitePalOpenHelper(mLitePalAttr.getDbName(),
                        mLitePalAttr.getVersion());
            }
            return mLitePalHelper;
        } else {
            throw new InvalidAttributesException("Uncaught invalid attributes exception happened");
        }
    }

}
